U.S. patent number 9,147,850 [Application Number 13/995,733] was granted by the patent office on 2015-09-29 for perylene-based semiconductors and methods of preparation and use thereof.
This patent grant is currently assigned to BASF SE, Polyera Corporation. The grantee listed for this patent is Zhihua Chen, Florian Doetz, Antonio Facchetti, Marcel Kastler, He Yan. Invention is credited to Zhihua Chen, Florian Doetz, Antonio Facchetti, Marcel Kastler, He Yan.
United States Patent |
9,147,850 |
Facchetti , et al. |
September 29, 2015 |
Perylene-based semiconductors and methods of preparation and use
thereof
Abstract
Provided are semiconductors prepared from an enantiomerically
enriched mixture of a nitrogen-functionalized rylene
bis(dicarboximide) compound. Specifically, the enantiomerically
enriched mixture has unexpected electron-transport efficiency
compared to the racemate or either of the enantiomers in optically
pure form.
Inventors: |
Facchetti; Antonio (Chicago,
IL), Chen; Zhihua (Skokie, IL), Yan; He (Kowloon,
HK), Kastler; Marcel (Mannheim, DE), Doetz;
Florian (Singapore, SG) |
Applicant: |
Name |
City |
State |
Country |
Type |
Facchetti; Antonio
Chen; Zhihua
Yan; He
Kastler; Marcel
Doetz; Florian |
Chicago
Skokie
Kowloon
Mannheim
Singapore |
IL
IL
N/A
N/A
N/A |
US
US
HK
DE
SG |
|
|
Assignee: |
BASF SE (Ludwigshafen,
DE)
Polyera Corporation (Skokie, IL)
|
Family
ID: |
46382378 |
Appl.
No.: |
13/995,733 |
Filed: |
December 19, 2011 |
PCT
Filed: |
December 19, 2011 |
PCT No.: |
PCT/IB2011/055760 |
371(c)(1),(2),(4) Date: |
June 19, 2013 |
PCT
Pub. No.: |
WO2012/090110 |
PCT
Pub. Date: |
July 05, 2012 |
Prior Publication Data
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|
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Document
Identifier |
Publication Date |
|
US 20130270543 A1 |
Oct 17, 2013 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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61428668 |
Dec 30, 2010 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L
51/0053 (20130101); H01L 51/0072 (20130101); C07D
471/06 (20130101); H01L 51/0545 (20130101); H01L
51/0541 (20130101) |
Current International
Class: |
H01L
29/08 (20060101); H01L 51/00 (20060101); C07D
471/06 (20060101); H01L 51/05 (20060101) |
Field of
Search: |
;257/40 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2008 063609 |
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May 2008 |
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WO |
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2008 085942 |
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Jul 2008 |
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WO |
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2009 098252 |
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Aug 2009 |
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WO |
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Other References
International Search Report Issued May 31, 2012 in PCT/IB11/55760
Filed Dec. 19, 2011. cited by applicant.
|
Primary Examiner: Menz; Douglas
Attorney, Agent or Firm: Oblon, McClelland, Maier &
Neustadt, L.L.P.
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATIONS
The present application is a 35 U.S.C. .sctn.371 national stage
patent application of International patent application
PCT/IB2011/055760, filed on Dec. 19, 2011, published as
WO/2012/090110 on Jul. 5, 2012, the text of which is incorporated
by reference, and claims the benefit of the filing date of U.S.
provisional application No. 61/428,668, filed on Dec. 30, 2010, the
text of which is also incorporated by reference.
Claims
The invention claimed is:
1. A thin film semiconductor comprising an enantiomerically
enriched mixture of a compound of formula I: ##STR00017## wherein:
R.sup.1 and R.sup.2 are identical or substantially identical and
are selected from the group consisting of a branched C.sub.4-40
alkyl group, a branched C.sub.4-40 alkenyl group, and a branched
C.sub.4-40 haloalkyl group; wherein the branched C.sub.4-40 alkyl
group, the branched C.sub.4-40 alkenyl group, and the branched
C.sub.4-40 haloalkyl group have a formula selected from the group
consisting of: ##STR00018## wherein R' is a C.sub.1-20 alkyl group
or a C.sub.1-20 haloalkyl group; R'' is different from R' and is
selected from the group consisting of a C.sub.1-20 alkyl group, a
C.sub.2-20 alkenyl group, and a C.sub.1-20 haloalkyl group; and an
asterisk (*) denotes a stereogenic center such that R.sup.1 and
R.sup.2 have either an R- or S-configuration; and wherein a ratio
of (R,R)-stereoisomers:(S,S)-stereoisomers or a ratio of
(S,S)-stereoisomers:(R,R)-stereoisomers of the compound of formula
I in the enantiomerically enriched mixture is between about 0.8:0.2
and about 0.98:0.02.
2. The thin film semiconductor of claim 1, wherein the
enantiomerically enriched mixture comprises two stereoisomers:
##STR00019## wherein R' is a C.sub.1-6 alkyl group or a C.sub.1-6
haloalkyl group; and R'' is different from R' and is selected from
the group consisting of a C.sub.3-20 alkyl group, a C.sub.3-20
alkenyl group, and a C.sub.3-20 haloalkyl group; and a relative
ratio of the two stereoisomers is between about 0.8:0.2 and about
0.98:0.02.
3. The thin film semiconductor of claim 1, wherein the
enantiomerically enriched mixture comprises two stereoisomers:
##STR00020## wherein R' is a C.sub.1-6 alkyl group or a C.sub.1-6
haloalkyl group; and R'' is different from R' and is selected from
the group consisting of a C.sub.3-20 alkyl group, a C.sub.3-20
alkenyl group, and a C.sub.3-20 haloalkyl group; and a relative
ratio of the two stereoisomers is between about 0.8:0.2 and about
0.98:0.02.
4. The thin film semiconductor of claim 1, wherein the
enantiomerically enriched mixture comprises two stereoisomers:
##STR00021## wherein R' is a C.sub.1-6 alkyl group or a C.sub.1-6
haloalkyl group; and R'' is different from R' and is selected from
the group consisting of a C.sub.3-20 alkyl group, a C.sub.3-20
alkenyl group, and a C.sub.3-20 haloalkyl group; and a relative
ratio of the two stereoisomers is between about 0.8:0.2 and about
0.98:0.02.
5. The thin film semiconductor of claim 2, wherein R' is selected
from the group consisting of CH.sub.3, CF.sub.3, C.sub.2H.sub.5,
CH.sub.2CF.sub.3, and C.sub.2F.sub.5.
6. The thin film semiconductor of claim 1, wherein the
enantiomerically enriched mixture comprises two stereoisomers:
##STR00022## wherein a relative ratio of the two stereoisomers is
between about 0.8:0.2 and about 0.98:0.02.
7. The thin film semiconductor of claim 1, wherein the
enantiomerically enriched mixture comprises two stereoisomers:
##STR00023## wherein a relative ratio of the two stereoisomers is
between about 0.8:0.2 and about 0.98:0.02.
8. The thin film semiconductor of claim 1, wherein the
enantiomerically enriched mixture comprises two stereoisomers:
##STR00024## wherein a relative ratio of the two stereoisomers is
between about 0.8:0.2 and about 0.98:0.02.
9. The thin film semiconductor of claim 1, wherein the
enantiomerically enriched mixture comprises two stereoisomers:
##STR00025## wherein a relative ratio of the two stereoisomers is
between about 0.8:0.2 and about 0.98:0.02.
10. The thin film semiconductor of claim 1, wherein the
enantiomerically enriched mixture comprises two stereoisomers:
##STR00026## wherein a relative ratio of the two stereoisomers is
between about 0.8:0.2 and about 0.98:0.02.
11. The thin film semiconductor of any one of claim 1, wherein the
ratio of (R,R)-stereoisomers:(S,S)-stereoisomers or the ratio of
(S,S)- stereoisomers: (R,R)-stereoisomers is between about
0.90:0.10 and about 95:0.05.
12. A composite comprising a substrate and the thin film
semiconductor of claim 1 deposited on the substrate.
13. An electronic device, an optical device, or an optoelectronic
device comprising the thin film semiconductor of claim 1.
14. An electronic device, an optical device, or an optoelectronic
device comprising the composite of claim 12.
15. A field effect transistor device comprising a source electrode,
a drain electrode, a gate electrode, and the thin film
semiconductor of claim 1 in contact with a dielectric material.
16. The field effect transistor device of claim 15, wherein the
field effect transistor has a structure selected from the group
consisting of a top-gate bottom-contact structure, a bottom-gate
top-contact structure, a top-gate top-contact structure, and a
bottom-gate bottom-contact structure.
17. The field effect transistor device of claim 15, wherein the
dielectric material comprises an organic dielectric material, an
inorganic dielectric material, or a hybrid organic/inorganic
dielectric material.
18. The field effect transistor device of claim 15, wherein the
field effect transistor device exhibits a field effect mobility
that is at least twice as high as an otherwise identical field
effect transistor device comprising a thin film semiconductor
comprising a 1:1 mixture of the (R,R)-stereoisomers and the
(S,S)-stereoisomers of the compound of formula I.
19. The thin film semiconductor of claim 3, wherein R' is selected
from the group consisting of CH.sub.3, CF.sub.3, C.sub.2H.sub.5,
CH.sub.2CF.sub.3, and C.sub.2F.sub.5.
20. The thin film semiconductor of claim 4, wherein R' is selected
from the group consisting of CH.sub.3, CF.sub.3, C.sub.2H.sub.5,
CH.sub.2CF.sub.3, and C.sub.2F.sub.5.
Description
BACKGROUND
Recent developments in organic-based light-emitting diodes (OLEDs),
photovoltaics (OPVs), and field-effect transistors (OFETs) have
opened up many opportunities in the field of organic electronics.
One of the challenges in this field is to develop thin film devices
that have environmentally stable electron-transporting (n-type)
organic semiconductors with high-mobility. The performance and
stability of organic n-type materials have significantly lagged
behind their p-type counterparts. Some challenges for advancing the
technology of organic n-type materials include their vulnerability
to ambient conditions (e.g., air) and solution-processability. For
example, it is desirable for these materials to be soluble in
common solvents so that they can be formulated into inks for
inexpensive printing processes.
The most common air-stable n-type organic semiconductors include
perfluorinated copper phthalocyanine (CuF.sub.16Pc), fluoroacyl
oligothiophenes (e.g., DFCO-4TCO), N,N'-fluorocarbon-substituted
naphthalene diimides (e.g., NDI-F, NDI-XF), cyano-substituted
perylene bis(dicarboximide)s (e.g., PDI-FCN.sub.2), and
cyano-substituted naphthalene bis(dicarboximide)s (e.g.,
NDI-8CN.sub.2). See, e.g., Bao et al. (1998), J. Am. Chem. Soc.,
120: 207-208; de Oteyza et al. (2005), Appl. Phys. Lett., 87:
183504; Schon et al. (2000), Adv Mater. 12: 1539-1542; Ye et al.
(2005), Appl. Phys. Lett., 86: 253505; Yoon et al. (2006), J. Am.
Chem. Soc., 128: 12851-12869; Tong et al. (2006), J. Phys. Chem.
B., 110: 17406-17413; Yuan et al. (2004), Thin Solid Films, 450:
316-319; Yoon et al. (2005), J. Am. Chem. Soc., 127: 1348-1349;
Katz et al. (2000), J. Am. Chem. Soc., 122: 7787-7792; Katz et al.
(2000), Nature (London), 404: 478-481; Katz et al (2001), Chem.
Phys. Chem., 3: 167-172; Jung et al. (2006), Appl. Phys. Lett., 88:
183102; Yoo et al. (2006), IEEE Electron Device Lett., 27: 737-739;
Jones et al. (2004), Angew. Chem., Int. Ed. Engl., 43: 6363-6366;
and Jones et al. (2007), J. Am. Chem. Soc., 129: 15259-15278.
Rylene bis(dicarboximide)s are particularly attractive because of
their robust nature, flexible molecular orbital energetics, and
excellent charge transport properties. However, high-mobility
rylene compounds, including PDI-FCN.sub.2 and NDI-F, have poor
solubility. Soluble rylene compounds, on the other hand, usually
have poor charge transport properties.
Accordingly, given potential applications in inexpensive and
large-area organic electronics that can be produced by
high-throughput reel-to-reel manufacture, the art desires new
organic semiconductor materials, especially those possessing
desirable properties such as air stability, high charge transport
efficiency, and good solubility in common solvents.
SUMMARY
In light of the foregoing, the present teachings provide organic
semiconductors and related compositions, composites, and/or devices
that can address various deficiencies and shortcomings of the
state-of-the-art, including those outlined above.
More specifically, the present teachings provide organic
semiconductors prepared from an enantiomerically enriched mixture
of a nitrogen-functionalized rylene bis(dicarboximide) compound. In
particular, the substituent of each of the two imide nitrogen atoms
of the compound includes a stereogenic center and has either an
(R)- or an (S)-configuration. It was surprisingly found that an
enantiomerically enriched mixture in which the ratio of the
(R,R)-stereoisomers to the (S,S)-stereoisomers (or vice versa) is
between about 0.8:0.2 and about 0.98:0.02 can lead to highly
improved electronic properties when compared to a 1:1 (or racemic)
mixture of the (R,R)- and (S,S)-stereoisomers. Specifically, when
incorporated as the semiconductor in a thin film transistor, the
enantiomerically enriched mixture of the present teachings can
exhibit a mobility that is at least two times and in some cases, as
much as six times higher than a racemic mixture of the same
compound. In addition, it was surprisingly found that the
enantiomerically enriched mixture of the present teachings has
substantially similar, and in some cases, better electronic
properties compared to either of the optically pure isomers.
The foregoing as well as other features and advantages of the
present teachings will be more fully understood from the following
figures, description, and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
It should be understood that the drawings described below are for
illustration purposes only. The drawings are not necessarily to
scale, with emphasis generally being placed upon illustrating the
principles of the present teachings. The drawings are not intended
to limit the scope of the present teachings in any way.
FIG. 1 illustrates four different configurations of thin film
transistors: bottom-gate top contact (top left), bottom-gate
bottom-contact (top right), top-gate bottom-contact (bottom left),
and top-gate top-contact (bottom right); each of which can be used
to incorporate polymers of the present teachings.
FIG. 2 compares the mobilities of thin film transistors obtained
with enantiomerically enriched bis(dicarboximide) mixtures
according to the present teachings with those obtained with racemic
mixtures and optically pure enantiomers of the bis(dicarboximide).
The enantiomerically enriched bis(dicarboximide) mixtures were
prepared from stereospecific amines.
FIG. 3 compares the mobilities of thin film transistors obtained
with enantiomerically enriched bis(dicarboximide) mixtures
according to the present teachings with those obtained with racemic
mixtures and optically pure enantiomers of the bis(dicarboximide).
The enantiomerically enriched bis(dicarboximide) mixtures were
prepared from enantiomerically enriched amine mixtures.
DETAILED DESCRIPTION
Throughout the application, where compositions are described as
having, including, or comprising specific components, or where
processes are described as having, including, or comprising
specific process steps, it is contemplated that compositions of the
present teachings also consist essentially of, or consist of, the
recited components, and that the processes of the present teachings
also consist essentially of, or consist of, the recited process
steps.
In the application, where an element or component is said to be
included in and/or selected from a list of recited elements or
components, it should be understood that the element or component
can be any one of the recited elements or components, or the
element or component can be selected from a group consisting of two
or more of the recited elements or components. Further, it should
be understood that elements and/or features of a composition, an
apparatus, or a method described herein can be combined in a
variety of ways without departing from the spirit and scope of the
present teachings, whether explicit or implicit herein.
The use of the terms "include," "includes", "including," "have,"
"has," or "having" should be generally understood as open-ended and
non-limiting unless specifically stated otherwise.
The use of the singular herein includes the plural (and vice versa)
unless specifically stated otherwise. In addition, where the use of
the term "about" is before a quantitative value, the present
teachings also include the specific quantitative value itself,
unless specifically stated otherwise. As used herein, the term
"about" refers to a .+-.10% variation from the nominal value unless
otherwise indicated or inferred.
It should be understood that the order of steps or order for
performing certain actions is immaterial so long as the present
teachings remain operable. Moreover, two or more steps or actions
may be conducted simultaneously.
As used herein, a "p-type semiconductor material" or a "donor"
material refers to a semiconductor material, for example, an
organic semiconductor material, having holes as the majority
current or charge carriers. In some embodiments, when a p-type
semiconductor material is deposited on a substrate, it can provide
a hole mobility in excess of about 10.sup.-5 cm.sup.2/Vs. In the
case of field-effect devices, a p-type semiconductor also can
exhibit a current on/off ratio of greater than about 10.
As used herein, an "n-type semiconductor material" or an "acceptor"
material refers to a semiconductor material, for example, an
organic semiconductor material, having electrons as the majority
current or charge carriers. In some embodiments, when an n-type
semiconductor material is deposited on a substrate, it can provide
an electron mobility in excess of about 10.sup.-5 cm.sup.2/Vs. In
the case of field-effect devices, an n-type semiconductor also can
exhibit a current on/off ratio of greater than about 10.
As used herein, "mobility" refers to a measure of the velocity with
which charge carriers, for example, holes (or units of positive
charge) in the case of a p-type semiconductor material and
electrons (or units of negative charge) in the case of an n-type
semiconductor material, move through the material under the
influence of an electric field. This parameter, which depends on
the device architecture, can be measured using a field-effect
device or space-charge limited current measurements.
As used herein, a compound can be considered "ambient stable" or
"stable at ambient conditions" when a transistor incorporating the
compound as its semiconducting material exhibits a carrier mobility
that is maintained at about its initial measurement when the
compound is exposed to ambient conditions, for example, air,
ambient temperature, and humidity, over a period of time. For
example, a compound can be described as ambient stable if a
transistor incorporating the compound shows a carrier mobility that
does not vary more than 20% or more than 10% from its initial value
after exposure to ambient conditions, including, air, humidity and
temperature, over a 3 day, 5 day, or 10 day period.
As used herein, "solution-processable" refers to compounds (e.g.,
polymers), materials, or compositions that can be used in various
solution-phase processes including spin-coating, printing (e.g.,
inkjet printing, gravure printing, offset printing and the like),
spray coating, electrospray coating, drop casting, dip coating, and
blade coating.
As used herein, "halo" or "halogen" refers to fluoro, chloro,
bromo, and iodo.
As used herein, "oxo" refers to a double-bonded oxygen (i.e.,
.dbd.O).
As used herein, "alkyl" refers to a straight-chain or branched
saturated hydrocarbon group. Examples of alkyl groups include
methyl (Me), ethyl (Et), propyl (e.g., n-propyl and iso-propyl),
butyl (e.g., n-butyl, iso-butyl, sec-butyl, tert-butyl), pentyl
groups (e.g., n-pentyl, iso-pentyl, neo-pentyl), hexyl groups, and
the like. In various embodiments, an alkyl group can have 1 to 40
carbon atoms (i.e., C.sub.1-40 alkyl group), for example, 1-20
carbon atoms (i.e., C.sub.1-20 alkyl group). In some embodiments,
an alkyl group can have 1 to 6 carbon atoms, and can be referred to
as a "lower alkyl group." Examples of lower alkyl groups include
methyl, ethyl, propyl (e.g., n-propyl and iso-propyl), and butyl
groups (e.g., n-butyl, iso-butyl, sec-butyl, tert-butyl). In some
embodiments, alkyl groups can be substituted as described herein.
An alkyl group is generally not substituted with another alkyl
group, an alkenyl group, or an alkynyl group.
As used herein, "haloalkyl" refers to an alkyl group having one or
more halogen substituents. At various embodiments, a haloalkyl
group can have 1 to 40 carbon atoms (i.e., C.sub.1-40 haloalkyl
group), for example, 1 to 20 carbon atoms (i.e., C.sub.1-20
haloalkyl group). Examples of haloalkyl groups include CF.sub.3,
C.sub.2F.sub.5, CHF.sub.2, CH.sub.2F, CCl.sub.3, CHCl.sub.2,
CH.sub.2Cl, C.sub.2Cl.sub.5, and the like. Perhaloalkyl groups,
i.e., alkyl groups where all of the hydrogen atoms are replaced
with halogen atoms (e.g., CF.sub.3 and C.sub.2F.sub.5), are
included within the definition of "haloalkyl." For example, a
C.sub.1-40 haloalkyl group can have the formula
--C.sub.sH.sub.2s+1-tX.sup.0.sub.t, where X.sup.0, at each
occurrence, is F, Cl, Br or I, s is an integer in the range of 1 to
40, and t is an integer in the range of 1 to 81, provided that t is
less than or equal to 2s+1. Haloalkyl groups that are not
perhaloalkyl groups can be substituted as described herein.
As used herein, "alkoxy" refers to --O-alkyl group. Examples of
alkoxy groups include, but are not limited to, methoxy, ethoxy,
propoxy (e.g., n-propoxy and isopropoxy), t-butoxy, pentoxyl,
hexoxyl groups, and the like. The alkyl group in the --O-alkyl
group can be substituted as described herein.
As used herein, "alkylthio" refers to an --S-alkyl group (which, in
some cases, can be expressed as --S(O).sub.w-alkyl, wherein w is
0). Examples of alkylthio groups include, but are not limited to,
methylthio, ethylthio, propylthio (e.g., n-propylthio and
isopropylthio), t-butylthio, pentylthio, hexylthio groups, and the
like. The alkyl group in the --S-alkyl group can be substituted as
described herein.
As used herein, "alkenyl" refers to a straight-chain or branched
alkyl group having one or more carbon-carbon double bonds. Examples
of alkenyl groups include ethenyl, propenyl, butenyl, pentenyl,
hexenyl, butadienyl, pentadienyl, hexadienyl groups, and the like.
The one or more carbon-carbon double bonds can be internal (such as
in 2-butene) or terminal (such as in 1-butene). In various
embodiments, an alkenyl group can have 2 to 40 carbon atoms (i.e.,
C.sub.2-40 alkenyl group), for example, 2 to 20 carbon atoms (i.e.,
C.sub.2-20 alkenyl group). In some embodiments, alkenyl groups can
be substituted as described herein. An alkenyl group is generally
not substituted with another alkenyl group, an alkyl group, or an
alkynyl group.
As used herein, "alkynyl" refers to a straight-chain or branched
alkyl group having one or more triple carbon-carbon bonds. Examples
of alkynyl groups include ethynyl, propynyl, butynyl, pentynyl,
hexynyl, and the like. The one or more triple carbon-carbon bonds
can be internal (such as in 2-butyne) or terminal (such as in
1-butyne). In various embodiments, an alkynyl group can have 2 to
40 carbon atoms (i.e., C.sub.2-40 alkynyl group), for example, 2 to
20 carbon atoms (i.e., C.sub.2-20 alkynyl group). In some
embodiments, alkynyl groups can be substituted as described herein.
An alkynyl group is generally not substituted with another alkynyl
group, an alkyl group, or an alkenyl group.
As used herein, a "cyclic moiety" can include one or more (e.g.,
1-6) carbocyclic or heterocyclic rings. The cyclic moiety can be a
cycloalkyl group, a heterocycloalkyl group, an aryl group, or a
heteroaryl group (i.e., can include only saturated bonds, or can
include one or more unsaturated bonds regardless of aromaticity),
each including, for example, 3-24 ring atoms and optionally can be
substituted as described herein. In embodiments where the cyclic
moiety is a "monocyclic moiety," the "monocyclic moiety" can
include a 3-14 membered aromatic or non-aromatic, carbocyclic or
heterocyclic ring. A monocyclic moiety can include, for example, a
phenyl group or a 5- or 6-membered heteroaryl group, each of which
optionally can be substituted as described herein. In embodiments
where the cyclic moiety is a "polycyclic moiety," the "polycyclic
moiety" can include two or more rings fused to each other (i.e.,
sharing a common bond) and/or connected to each other via a spiro
atom, or one or more bridged atoms. A polycyclic moiety can include
an 8-24 membered aromatic or non-aromatic, carbocyclic or
heterocyclic ring, such as a C.sub.8-24 aryl group or an 8-24
membered heteroaryl group, each of which optionally can be
substituted as described herein.
As used herein, "cycloalkyl" refers to a non-aromatic carbocyclic
group including cyclized alkyl, alkenyl, and alkynyl groups. In
various embodiments, a cycloalkyl group can have 3 to 24 carbon
atoms, for example, 3 to 20 carbon atoms (e.g., C.sub.3-14
cycloalkyl group). A cycloalkyl group can be monocyclic (e.g.,
cyclohexyl) or polycyclic (e.g., containing fused, bridged, and/or
spiro ring systems), where the carbon atoms are located inside or
outside of the ring system. Any suitable ring position of the
cycloalkyl group can be covalently linked to the defined chemical
structure. Examples of cycloalkyl groups include cyclopropyl,
cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclopentenyl,
cyclohexenyl, cyclohexadienyl, cycloheptatrienyl, norbornyl,
norpinyl, norcaryl, adamantyl, and spiro[4.5]decanyl groups, as
well as their homologs, isomers, and the like. In some embodiments,
cycloalkyl groups can be substituted as described herein.
As used herein, "heteroatom" refers to an atom of any element other
than carbon or hydrogen and includes, for example, nitrogen,
oxygen, silicon, sulfur, phosphorus, and selenium.
As used herein, "cycloheteroalkyl" refers to a non-aromatic
cycloalkyl group that contains at least one ring heteroatom
selected from O, S, Se, N, P, and Si (e.g., O, S, and N), and
optionally contains one or more double or triple bonds. A
cycloheteroalkyl group can have 3 to 24 ring atoms, for example, 3
to 20 ring atoms (e.g., 3-14 membered cycloheteroalkyl group). One
or more N, P, S, or Se atoms (e.g., N or S) in a cycloheteroalkyl
ring may be oxidized (e.g., morpholine N-oxide, thiomorpholine
S-oxide, thiomorpholine S,S-dioxide). In some embodiments, nitrogen
or phosphorus atoms of cycloheteroalkyl groups can bear a
substituent, for example, a hydrogen atom, an alkyl group, or other
substituents as described herein. Cycloheteroalkyl groups can also
contain one or more oxo groups, such as oxopiperidyl,
oxooxazolidyl, dioxo(1H,3H)-pyrimidyl, oxo-2(1H)-pyridyl, and the
like. Examples of cycloheteroalkyl groups include, among others,
morpholinyl, thiomorpholinyl, pyranyl, imidazolidinyl,
imidazolinyl, oxazolidinyl, pyrazolidinyl, pyrazolinyl,
pyrrolidinyl, pyrrolinyl, tetrahydrofuranyl, tetrahydrothiophenyl,
piperidinyl, piperazinyl, and the like. In some embodiments,
cycloheteroalkyl groups can be substituted as described herein.
As used herein, "aryl" refers to an aromatic monocyclic hydrocarbon
ring system or a polycyclic ring system in which two or more
aromatic hydrocarbon rings are fused (i.e., having a bond in common
with) together or at least one aromatic monocyclic hydrocarbon ring
is fused to one or more cycloalkyl and/or cycloheteroalkyl rings.
An aryl group can have 6 to 24 carbon atoms in its ring system
(e.g., C.sub.6-20 aryl group), which can include multiple fused
rings. In some embodiments, a polycyclic aryl group can have 8 to
24 carbon atoms. Any suitable ring position of the aryl group can
be covalently linked to the defined chemical structure. Examples of
aryl groups having only aromatic carbocyclic ring(s) include
phenyl, 1-naphthyl (bicyclic), 2-naphthyl (bicyclic), anthracenyl
(tricyclic), phenanthrenyl (tricyclic), pentacenyl (pentacyclic),
and like groups. Examples of polycyclic ring systems in which at
least one aromatic carbocyclic ring is fused to one or more
cycloalkyl and/or cycloheteroalkyl rings include, among others,
benzo derivatives of cyclopentane (i.e., an indanyl group, which is
a 5,6-bicyclic cycloalkyl/aromatic ring system), cyclohexane (i.e.,
a tetrahydronaphthyl group, which is a 6,6-bicyclic
cycloalkyl/aromatic ring system), imidazoline (i.e., a
benzimidazolinyl group, which is a 5,6-bicyclic
cycloheteroalkyl/aromatic ring system), and pyran (i.e., a
chromenyl group, which is a 6,6-bicyclic cycloheteroalkyl/aromatic
ring system). Other examples of aryl groups include benzodioxanyl,
benzodioxolyl, chromanyl, indolinyl groups, and the like. In some
embodiments, aryl groups can be substituted as described herein. In
some embodiments, an aryl group can have one or more halogen
substituents, and can be referred to as a "haloaryl" group.
Perhaloaryl groups, i.e., aryl groups where all of the hydrogen
atoms are replaced with halogen atoms (e.g., --C.sub.6F.sub.5), are
included within the definition of "haloaryl." In certain
embodiments, an aryl group is substituted with another aryl group
and can be referred to as a biaryl group. Each of the aryl groups
in the biaryl group can be substituted as disclosed herein.
As used herein, "heteroaryl" refers to an aromatic monocyclic ring
system containing at least one ring heteroatom selected from oxygen
(O), nitrogen (N), sulfur (S), silicon (Si), and selenium (Se) or a
polycyclic ring system where at least one of the rings present in
the ring system is aromatic and contains at least one ring
heteroatom. Polycyclic heteroaryl groups include those having two
or more heteroaryl rings fused together, as well as those having at
least one monocyclic heteroaryl ring fused to one or more aromatic
carbocyclic rings, non-aromatic carbocyclic rings, and/or
non-aromatic cycloheteroalkyl rings. A heteroaryl group, as a
whole, can have, for example, 5 to 24 ring atoms and contain 1-5
ring heteroatoms (i.e., 5-20 membered heteroaryl group). The
heteroaryl group can be attached to the defined chemical structure
at any heteroatom or carbon atom that results in a stable
structure. Generally, heteroaryl rings do not contain O--O, S--S,
or S--O bonds. However, one or more N or S atoms in a heteroaryl
group can be oxidized (e.g., pyridine N-oxide, thiophene S-oxide,
thiophene S,S-dioxide). Examples of heteroaryl groups include, for
example, the 5- or 6-membered monocyclic and 5-6 bicyclic ring
systems shown below:
##STR00001## where T is O, S, NH, N-alkyl, N-aryl, N-(arylalkyl)
(e.g., N-benzyl), SiH.sub.2, SiH(alkyl), Si(alkyl).sub.2,
SiH(arylalkyl), Si(arylalkyl).sub.2, or Si(alkyl)(arylalkyl).
Examples of such heteroaryl rings include pyrrolyl, furyl, thienyl,
pyridyl, pyrimidyl, pyridazinyl, pyrazinyl, triazolyl, tetrazolyl,
pyrazolyl, imidazolyl, isothiazolyl, thiazolyl, thiadiazolyl,
isoxazolyl, oxazolyl, oxadiazolyl, indolyl, isoindolyl, benzofuryl,
benzothienyl, quinolyl, 2-methylquinolyl, isoquinolyl, quinoxalyl,
quinazolyl, benzotriazolyl, benzimidazolyl, benzothiazolyl,
benzisothiazolyl, benzisoxazolyl, benzoxadiazolyl, benzoxazolyl,
cinnolinyl, 1H-indazolyl, 2H-indazolyl, indolizinyl, isobenzofuyl,
naphthyridinyl, phthalazinyl, pteridinyl, purinyl,
oxazolopyridinyl, thiazolopyridinyl, imidazopyridinyl,
furopyridinyl, thienopyridinyl, pyridopyrimidinyl, pyridopyrazinyl,
pyridopyridazinyl, thienothiazolyl, thienoxazolyl, thienoimidazolyl
groups, and the like. Further examples of heteroaryl groups include
4,5,6,7-tetrahydroindolyl, tetrahydroquinolinyl,
benzothienopyridinyl, benzofuropyridinyl groups, and the like. In
some embodiments, heteroaryl groups can be substituted as described
herein.
As used herein, "arylalkyl" refers to an -alkyl-aryl group, where
the arylalkyl group is covalently linked to the defined chemical
structure via the alkyl group. An arylalkyl group is within the
definition of a --Y--C.sub.6-14 aryl group, where Y is as defined
herein. An example of an arylalkyl group is a benzyl group
(--CH.sub.2--C.sub.6H.sub.5). An arylalkyl group optionally can be
substituted, i.e., the aryl group and/or the alkyl group, can be
substituted as disclosed herein.
Compounds of the present teachings can include a "divalent group"
defined herein as a linking group capable of forming a covalent
bond with two other moieties. For example, compounds of the present
teachings can include a divalent C.sub.1-20 alkyl group (e.g., a
methylene group), a divalent C.sub.2-20 alkenyl group (e.g., a
vinylyl group), a divalent C.sub.2-20 alkynyl group (e.g., an
ethynylyl group). a divalent C.sub.6-14 aryl group (e.g., a
phenylyl group); a divalent 3-14 membered cycloheteroalkyl group
(e.g., a pyrrolidylyl), and/or a divalent 5-14 membered heteroaryl
group (e.g., a thienylyl group). Generally, a chemical group (e.g.,
--Ar--) is understood to be divalent by the inclusion of the two
bonds before and after the group.
As used herein, a "solubilizing group" refers to a functional group
that makes the resultant molecule more soluble in at least one
common organic solvent than a hydrogen atom would if it occupied
the same position in a molecule (for the same molecule-solvent
combination). Examples of solubilizing groups include alkyl groups
(e.g., methyl, ethyl, iso-propyl, n-propyl, iso-butyl, sec-butyl,
n-butyl, tert-butyl, n-pentyl, iso-pentyl, neo-pentyl, hexyl,
20methyl hexyl, octyl, 3,7-dimethyl octyl, decyl, deodecyl,
tetradecyl, hexadecyl), alkoxy groups (e.g., methoxy, ethoxy,
iso-propoxy, n-propoxy, iso-butyloxy, sec-butyloxy, n-butyloxy,
hexyloxy, 2-methyl hexyloxy, octyloxy, 3,7-dimethyl octyloxy,
decyloxy, dodecyloxy, tetradecyloxy, hexadecyloxy), thioalkyl
groups (e.g., thiooctyl), alkyethers, and thioethers.
As used herein, a "leaving group" ("LG") refers to a charged or
uncharged atom (or group of atoms) that can be displaced as a
stable species as a result of, for example, a substitution or
elimination reaction. Examples of leaving groups include, but are
not limited to, halogen (e.g., Cl, Br, I), azide (N3), thiocyanate
(SCN), nitro (NO.sub.2), cyanate (CN), water (H.sub.2O), ammonia
(NH.sub.3), and sulfonate groups (e.g., OSO.sub.2--R, wherein R can
be a C.sub.1-10 alkyl group or a C.sub.6-14 aryl group each
optionally substituted with 1-4 groups independently selected from
a C.sub.1-10 alkyl group and an electron-withdrawing group) such as
tosylate (toluenesulfonate, OTs), mesylate (methanesulfonate, OMs),
brosylate (p-bromobenzenesulfonate, OBs), nosylate
(4-nitrobenzenesulfonate, ONs), and triflate
(trifluoromethanesulfonate, OTf).
As used herein, a "cyanating agent" can be LiCN, NaCN, KCN, CuCN,
AgCN, trimethylsilyl cyanide (TMSCN), or any other cyanating agent
known by those skilled in the art.
The electron-donating or electron-withdrawing properties of several
hundred of the most common substituents, reflecting all common
classes of substituents have been determined, quantified, and
published. The most common quantification of electron-donating and
electron-withdrawing properties is in terms of Hammett G values.
Hydrogen has a Hammett G value of zero, while other substituents
have Hammett G values that increase positively or negatively in
direct relation to their electron-withdrawing or electron-donating
characteristics. Substituents with negative Hammett G values are
considered electron-donating, while those with positive Hammett G
values are considered electron-withdrawing. See Lange's Handbook of
Chemistry, 12th ed., McGraw Hill, 1979, Table 3-12, pp. 3-134 to
3-138, which lists Hammett G values for a large number of commonly
encountered substituents and is incorporated by reference
herein.
It should be understood that the term "electron-accepting group"
can be used synonymously herein with "electron acceptor" and
"electron-withdrawing group". In particular, an
"electron-withdrawing group" ("EWG") or an "electron-accepting
group" or an "electron-acceptor" refers to a functional group that
draws electrons to itself more than a hydrogen atom would if it
occupied the same position in a molecule. Examples of
electron-withdrawing groups include, but are not limited to,
halogen or halo (e.g., F, Cl, Br, I), --NO.sub.2, --CN, --NC,
--S(R.sup.0).sub.2.sup.+, --N(R.sup.0).sub.3.sup.+, --SO.sub.3H,
--SO.sub.2R.sup.0, --SO.sub.3R.sup.0, --SO.sub.2NHR.sup.0,
--SO.sub.2N(R.sup.0).sub.2, --COOH, --COR.sup.0, --COOR.sup.0,
--CONHR.sup.0, --CON(R.sup.0).sub.2, C.sub.1-40 haloalkyl groups,
C.sub.6-14 aryl groups, and 5-14 membered electron-poor heteroaryl
groups; where R.sup.0 is a C.sub.1-20 alkyl group, a C.sub.2-20
alkenyl group, a C.sub.2-20 alkynyl group, a C.sub.1-20 haloalkyl
group, a C.sub.1-20 alkoxy group, a C.sub.6-14 aryl group, a
C.sub.3-14 cycloalkyl group, a 3-14 membered cycloheteroalkyl
group, and a 5-14 membered heteroaryl group, each of which
optionally can be substituted as described herein. For example,
each of the C.sub.1-20 alkyl group, the C.sub.2-20 alkenyl group,
the C.sub.2-20 alkynyl group, the C.sub.1-20 haloalkyl group, the
C.sub.1-20 alkoxy group, the C.sub.6-14 aryl group, the C.sub.3-14
cycloalkyl group, the 3-14 membered cycloheteroalkyl group, and the
5-14 membered heteroaryl group optionally can be substituted with
1-5 small electron-withdrawing groups such as F, Cl, Br,
--NO.sub.2, --CN, --NC, --S(R.sup.0).sub.2.sup.+,
--N(R.sup.0).sub.3.sup.+, --SO.sub.3H, --SO.sub.2R.sup.0,
--SO.sub.3R.sup.0, --SO.sub.2NHR.sup.0, --SO.sub.2N(R.sup.0).sub.2,
--COOH, --COR.sup.0, --COOR.sup.0, --CONHR.sup.0, and
--CON(R.sup.0).sub.2.
It should be understood that the term "electron-donating group" can
be used synonymously herein with "electron donor". In particular,
an "electron-donating group" or an "electron-donor" refers to a
functional group that donates electrons to a neighboring atom more
than a hydrogen atom would if it occupied the same position in a
molecule. Examples of electron-donating groups include --OH,
--OR.sup.0, --NH.sub.2, --NHR.sup.0, --N(R.sup.0).sub.2, and 5-14
membered electron-rich heteroaryl groups, where R.sup.0 is a
C.sub.1-20 alkyl group, a C.sub.2-20 alkenyl group, a C.sub.2-20
alkynyl group, a C.sub.6-14 aryl group, or a C.sub.3-14 cycloalkyl
group.
Various unsubstituted heteroaryl groups can be described as
electron-rich (or .pi.-excessive) or electron-poor (or
.pi.-deficient). Such classification is based on the average
electron density on each ring atom as compared to that of a carbon
atom in benzene. Examples of electron-rich systems include
5-membered heteroaryl groups having one heteroatom such as furan,
pyrrole, and thiophene; and their benzofused counterparts such as
benzofuran, benzopyrrole, and benzothiophene. Examples of
electron-poor systems include 6-membered heteroaryl groups having
one or more heteroatoms such as pyridine, pyrazine, pyridazine, and
pyrimidine; as well as their benzofused counterparts such as
quinoline, isoquinoline, quinoxaline, cinnoline, phthalazine,
naphthyridine, quinazoline, phenanthridine, acridine, and purine.
Mixed heteroaromatic rings can belong to either class depending on
the type, number, and position of the one or more heteroatom(s) in
the ring. See Katritzky, A. R and Lagowski, J. M., Heterocyclic
Chemistry (John Wiley & Sons, New York, 1960).
At various places in the present specification, substituents are
disclosed in groups or in ranges. It is specifically intended that
the description include each and every individual subcombination of
the members of such groups and ranges. For example, the term
"C.sub.1-6 alkyl" is specifically intended to individually disclose
C.sub.1, C.sub.2, C.sub.3, C.sub.4, C.sub.5, C.sub.6,
C.sub.1-C.sub.6, C.sub.1-C.sub.5, C.sub.1-C.sub.4, C.sub.1-C.sub.3,
C.sub.1-C.sub.2, C.sub.2-C.sub.6, C.sub.2-C.sub.5, C.sub.2-C.sub.4,
C.sub.2-C.sub.3, C.sub.3-C.sub.6, C.sub.3-C.sub.5, C.sub.3-C.sub.4,
C.sub.4-C.sub.6, C.sub.4-C.sub.5, and C.sub.5-C.sub.6 alkyl. By way
of other examples, an integer in the range of 0 to 40 is
specifically intended to individually disclose 0, 1, 2, 3, 4, 5, 6,
7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,
24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, and
40, and an integer in the range of 1 to 20 is specifically intended
to individually disclose 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13,
14, 15, 16, 17, 18, 19, and 20. Additional examples include that
the phrase "optionally substituted with 1-5 substituents" is
specifically intended to individually disclose a chemical group
that can include 0, 1, 2, 3, 4, 5, 0-5, 0-4, 0-3, 0-2, 0-1, 1-5,
1-4, 1-3, 1-2, 2-5, 2-4, 2-3, 3-5, 3-4, and 4-5 substituents.
Throughout the specification, structures may or may not be
presented with chemical names. Where any question arises as to
nomenclature, the structure prevails.
Generally, the present teachings relate to a thin film
semiconductor comprising an enantiomerically enriched mixture of a
compound of formula I:
##STR00002## where R.sup.1 and R.sup.2 are compositionally
identical or substantially identical branched organic groups that
include a stereogenic center. While formula I is intended to
include various possible regioisomers, it is intended that formula
I encompasses, at a minimum, the isomers:
##STR00003## which are known to be the most kinetically stable
among the various possible regioisomers of formula I.
More specifically, in certain embodiments, R.sup.1 and R.sup.2 can
be identical and selected from a branched C.sub.4-40 alkyl group, a
branched C.sub.4-40 alkenyl group and a branched C.sub.4-40
haloalkyl group, where the branched C.sub.4-40 alkyl group, the
branched C.sub.4-40 alkenyl group, or the branched C.sub.4-40
haloalkyl group can have a formula selected from:
##STR00004## where R' is a C.sub.1-20 alkyl or haloalkyl group; and
R'' is different from R' and selected from a C.sub.1-20 alkyl
group, a C.sub.2-20 alkenyl group, and a C.sub.1-20 haloalkyl
group. The asterisk * denotes a stereogenic center such that
R.sup.1 and R.sup.2 have either an (R)- or an (S)-configuration.
The mixture is enantiomerically enriched, that is, the mixture
includes an excess of either the (R,R)-stereoisomer (in which both
R.sup.1 and R.sup.2 have the (R)-configuration) or the
(S,S)-stereoisomer (in which both R.sup.1 and R.sup.2 have the
(S)-configuration). More specifically, the ratio of
(R,R)-stereoisomers:(S,S)-stereoisomers or the ratio of
[S,S]-stereoisomers:(R,R)-stereoisomers in the enantiomerically
enriched mixture is between about 0.8:0.2 and about 0.98:0.02.
In certain embodiments, R.sup.1 and R.sup.2 can be substantially
identical branched groups that include the same stereogenic center,
and independently can be a branched C.sub.4-40 alkyl group, a
branched C.sub.4-40 alkenyl group, or a branched C.sub.4-40
haloalkyl group. In embodiments where R.sup.1 and R.sup.2 are
described as being "substantially identical," it is intended to
mean that while both R.sup.1 and R.sup.2 have the same branching
pattern including a stereogenic center as represented by one of the
formulae:
##STR00005## one of R' and R'' can be different, for example, in
terms of the number of carbon atoms (e.g., a difference of no more
than two carbon atoms), the extent of saturation, or substitution
with halogen groups. To illustrate, R.sup.1 and R.sup.2 can be
considered substantially identical when both R.sup.1 and R.sup.2
are a branched group of the formula:
##STR00006## where R' is the same in both R.sup.1 and R.sup.2, but
R'' in R.sup.1 is different from R'' in R.sup.2. For example, R''
in R.sup.1 can be an n-hexyl group, but R'' in R.sup.2 can be an
n-pentyl group, an n-heptyl group, a hexenyl group, or a
fluoro-substituted hexyl group (e.g.,
(CH.sub.2).sub.5CF.sub.3).
In certain embodiments, the enantiomerically enriched mixture can
include a pair of enantiomers selected from:
##STR00007## ##STR00008## ##STR00009## where R' and R'' are as
defined herein, and the relative ratio of the two enantiomers in
each pair is between about 0.8:0.2 and about 0.98:0.02. In
particular embodiments, the relative ratio of the two enantiomers
in each pair can be between about 0.90:0.10 and about
0.95:0.05.
In particular embodiments, R' can be a lower alkyl or haloalkyl
group having 1 to 6 carbon atoms (e.g., CH.sub.3, CF.sub.3,
C.sub.2H.sub.5, C.sub.2F.sub.5, CH.sub.2CF.sub.3, C.sub.3H.sub.7,
C.sub.3F.sub.7, and CH.sub.2CH.sub.2CF.sub.3); while R'' is
different from R' and has at least 3 carbon atoms. For example, R''
can be selected from a C.sub.3-20 alkyl group, a C.sub.3-20 alkenyl
group, and a C.sub.3-20 haloalkyl group. In various embodiments,
both R' and R'' can be linear groups.
To further illustrate, an enantiomerically enriched mixture of the
present teachings can include a pair of enantiomers selected
from:
##STR00010## ##STR00011## ##STR00012## ##STR00013## where the
relative ratio of the two enantiomers in each pair is between about
0.8:0.2 and about 0.98:0.02. In particular embodiments, the
relative ratio of the two enantiomers in each pair can be between
about 0.90:0.10 and about 0.95:0.05.
The enantiomerically enriched mixture of the present teachings can
be obtained via different methods. A compound of formula I
typically can be synthesized by reacting a primary amine with a
dianhydride of formula II:
##STR00014## then reacting the resulting bis(dicarboximide) with a
cyanating agent to replace the leaving groups (LG) with cyano
groups. The primary amine can have a formula selected from:
##STR00015## where R' and R'' are as defined herein, and can be
prepared in accordance with the procedures outlined in Scheme 1
below.
##STR00016##
Referring to Scheme 1, ketoxime 2 can be prepared by mixing ketone
1 with hydroxylamine hydrochloride in methanol, followed by
addition of sodium acetate, at reflux temperature. To reduce the
ketoxime into the amine 3, a solution of ketoxime 2 in diethyl
ether can be added dropwise to a suspension of lithium aluminium
hydride in dry diethyl ether at 0.degree. C., then heated to reflux
for sixteen hours, to provide a racemic mixture of the amine 3.
Various procedures can be used to isolate optically pure
enantiomers of amine 3. For example, chiral separation,
diastereomeric salt formation, or kinetic resolution can be used.
In particular, kinetic resolution of racemates by enzyme-catalyzed
acyl transfer reactions can lead to a very high enantiomeric excess
(>99.0%). Various enzymes including Pseudomonas aeruginosa
lipase, subtilisin, and Candida antarctica lipase have been studied
for their efficiency in kinetic resolution of chiral amines. See,
e.g., Davis et al. (2001), Syn. Comm., 31(4): 569-578.
Accordingly, in some embodiments, an enantiomerically enriched
mixture of the present teachings can be obtained by using a
stereospecific primary amine. For example, an (R,R)-stereoisomer of
formula I can be obtained by reacting an (R)-amine with the
dianhydride of formula II, which is then combined at the
appropriate ratio with the (S,S)-stereoisomer obtained in an
analogous manner to provide an enantiomerically enriched mixture of
compounds of formula I.
In some embodiments, the present enantiomerically enriched mixture
can be prepared from an enantiomerically enriched mixture of the
primary amine. While reacting the dianhydride of formula II with an
enantiomerically enriched mixture of the primary amine (as opposed
to a stereospecific primary amine) will lead to some meso isomers
of compounds of formula I, it was found that the presence of the
meso isomers has little effect on the semiconducting properties of
the enantiomerically enriched mixture as a whole.
In alternative embodiments, the dianhydride of formula II can be
reacted with a racemic mixture of the primary amine, which leads to
a mixture of the (R,R)-stereoisomer, the (S,S)-stereoisomer, and
the achiral meso-(R,S)-stereoisomer. The (R,R)-stereoisomer, and
similarly, the (S,S)-stereoisomer, can be isolated using standard
separation procedures, and subsequently combined with the other
enantiomer at specific ratios to provide the present
enantiomerically enriched mixture. Standard separation procedures
known to those skilled in the art include, for example, column
chromatography, thin-layer chromatography, simulated moving-bed
chromatography, and high-performance liquid chromatography,
optionally with chiral stationary phases.
The enantiomerically enriched mixture of the present teachings can
be used to prepare semiconductor materials (e.g., compositions and
composites), which in turn can be used to fabricate various
articles of manufacture, structures, and devices. In some
embodiments, semiconductor materials incorporating the
enantiomerically enriched mixture of the present teachings can
exhibit n-type semiconducting activity. It was surprisingly found
that an enantiomerically enriched mixture of a compound of formula
I according to the present teachings can exhibit highly improved
electronic properties when compared to the racemate. Specifically,
when incorporated as the semiconductor in a thin film transistor,
the enantiomerically enriched mixture of the present teachings
exhibits a mobility that can be at least two times and in some
cases, as much as six times higher than the racemate. In addition,
it was surprisingly found that the enantiomerically enriched
mixture of the present teachings has substantially similar, and in
some cases, better electronic properties compared to either the
(R,R)-stereoisomer or the (S,S)-stereoisomer in substantially pure
form (i.e., an optical purity of 99% or greater).
Accordingly, the present teachings provide for electronic devices,
optical devices, and optoelectronic devices that include the
enantiomerically enriched mixture described herein. Examples of
such electronic devices, optical devices, and optoelectronic
devices include thin film semiconductors, thin film transistors
(e.g., field effect transistors), photovoltaics, photodetectors,
organic light emitting devices such as organic light emitting
diodes (OLEDs) and organic light emitting transistors (OLETs),
complementary metal oxide semiconductors (CMOSs), complementary
inverters, diodes, capacitors, sensors, D flip-flops, rectifiers,
and ring oscillators. In some embodiments, the present teachings
provide for a thin film semiconductor including the
enantiomerically enriched mixture described herein and a field
effect transistor device including the thin film semiconductor. In
particular, the field effect transistor device has a structure
selected from top-gate bottom-contact structure, bottom-gate
top-contact structure, top-gate top-contact structure, and
bottom-gate bottom-contact structure. In certain embodiments, the
field effect transistor device includes a dielectric material,
wherein the dielectric material includes an organic dielectric
material, an inorganic dielectric material, or a hybrid
organic/inorganic dielectric material. In other embodiments, the
present teachings provide for photovoltaic devices and organic
light emitting devices incorporating a thin film semiconductor that
includes the enantiomerically enriched mixture described
herein.
Compounds of formula I generally have good solubility in a variety
of common solvents. Thus, the present enantiomerically enriched
mixture can be processed via inexpensive solution-phase techniques
into various electronic devices, optical devices, and
optoelectronic devices. As used herein, a compound can be
considered soluble in a solvent when at least 1 mg of the compound
can be dissolved in 1 mL of the solvent. Examples of common organic
solvents include petroleum ethers; acetonitrile; aromatic
hydrocarbons such as benzene, toluene, xylene, and mesitylene;
ketones such as acetone and methyl ethyl ketone; ethers such as
tetrahydrofuran, dioxane, bis(2-methoxyethyl)ether, diethyl ether,
di-isopropyl ether, and t-butyl methyl ether; alcohols such as
methanol, ethanol, butanol, and isopropyl alcohol; aliphatic
hydrocarbons such as hexanes; acetates such as methyl acetate,
ethyl acetate, methyl formate, ethyl formate, isopropyl acetate,
and butyl acetate; amides such as dimethylformamide and
dimethylacetamide; sulfoxides such as dimethylsulfoxide;
halogenated aliphatic and aromatic hydrocarbons such as
dichloromethane, chloroform, ethylene chloride, chlorobenzene,
dichlorobenzene, and trichlorobenzene; and cyclic solvents such as
cyclopentanone, cyclohexanone, and 2-methypyrrolidone. Examples of
common inorganic solvents include water and ionic liquids.
Accordingly, the present teachings further provide compositions
that include the enantiomerically enriched mixture disclosed herein
dissolved or dispersed in a liquid medium, for example, an organic
solvent, an inorganic solvent, or combinations thereof (e.g., a
mixture of organic solvents, inorganic solvents, or organic and
inorganic solvents). In some embodiments, the composition can
further include one or more additives independently selected from
detergents, dispersants, binding agents, compatiblizing agents,
curing agents, initiators, humectants, antifoaming agents, wetting
agents, pH modifiers, biocides, and bactereriostats. For example,
surfactants and/or other polymers (e.g., polystyrene, polyethylene,
poly-alpha-methylstyrene, polyisobutene, polypropylene,
polymethylmethacrylate, and the like) can be included as a
dispersant, a binding agent, a compatiblizing agent, and/or an
antifoaming agent.
Various deposition techniques, including various
solution-processing techniques, have been used with organic
electronics. For example, much of the printed electronics
technology has focused on inkjet printing, primarily because this
technique offers greater control over feature position and
multilayer registration. Inkjet printing is a noncontact process,
which offers the benefits of not requiring a preformed master
(compared to contact printing techniques), as well as digital
control of ink ejection, thereby providing drop-on-demand printing.
However, contact printing techniques have the key advantage of
being well-suited for very fast roll-to-roll processing. Exemplary
contact printing techniques include screen-printing, gravure,
offset, flexo, and microcontact printing. Other solution processing
techniques include, for example, spin coating, drop-casting, zone
casting, dip coating, and blade coating.
The present enantiomerically enriched mixture can exhibit
versatility in their processing. Formulations including the present
enantiomerically enriched mixture can be printable via different
types of printing techniques including gravure printing,
flexographic printing, and inkjet printing, providing smooth and
uniform films that allow, for example, the formation of a
pinhole-free dielectric film thereon, and consequently, the
fabrication of all-printed devices.
The present teachings, therefore, further provide methods of
preparing a semiconductor material. The methods can include
preparing a composition that includes the present enantiomerically
enriched mixture disclosed herein dissolved or dispersed in a
liquid medium such as a solvent or a mixture of solvents,
depositing the composition on a substrate to provide a
semiconductor material precursor, and processing (e.g., heating)
the semiconductor precursor to provide a semiconductor material
(e.g., a thin film semiconductor) that includes the
enantiomerically enriched mixture disclosed herein. In some
embodiments, the depositing step can be carried out by printing,
including inkjet printing and various contact printing techniques
(e.g., screen-printing, gravure printing, offset printing, pad
printing, lithographic printing, flexographic printing, and
microcontact printing). In other embodiments, the depositing step
can be carried out by spin coating, drop-casting, zone casting, dip
coating, blade coating, or spraying. More expensive processes such
as vapor deposition also can be used.
The present teachings further provide articles of manufacture, for
example, composites that include a thin film semiconductor of the
present teachings and a substrate component and/or a dielectric
component. The substrate component can be selected from doped
silicon, an indium tin oxide (ITO), ITO-coated glass, ITO-coated
polyimide or other plastics, aluminum or other metals alone or
coated on a polymer or other substrate, a doped polythiophene, and
the like. The dielectric component can be prepared from inorganic
dielectric materials such as various oxides (e.g., SiO.sub.2,
Al.sub.2O.sub.3, HfO.sub.2), organic dielectric materials such as
various polymeric materials (e.g., polycarbonate, polyester,
polystyrene, polyhaloethylene, polyacrylate), self-assembled
superlattice/self-assembled nanodielectric (SAS/SAND) materials
(e.g., as described in Yoon, M-H. et al., PNAS, 102 (13): 4678-4682
(2005), the entire disclosure of which is incorporated by reference
herein), as well as hybrid organic/inorganic dielectric materials
(e.g., as described in U.S. Pat. No. 7,678,463, the entire
disclosure of which is incorporated by reference herein). In some
embodiments, the dielectric component can include the crosslinked
polymer blends described in U.S. Pat. No. 7,605,394, the entire
disclosure of which is incorporated by reference herein. The
composite also can include one or more electrical contacts.
Suitable materials for the source, drain, and gate electrodes
include metals (e.g., Au, Al, Ni, Cu), transparent conducting
oxides (e.g., ITO, IZO, ZITO, GZO, GIO, GITO), and conducting
polymers (e.g.,
poly(3,4-ethylenedioxythiophene)poly(styrenesulfonate) (PEDOT:PSS),
polyaniline (PANI), polypyrrole (PPy)). One or more of the
composites described herein can be embodied within various organic
electronic, optical, and optoelectronic devices such as organic
thin film transistors (OTFTs), specifically, organic field effect
transistors (OFETs), as well as sensors, capacitors, unipolar
circuits, complementary circuits (e.g., inverter circuits), and the
like.
Accordingly, an aspect of the present teachings relates to methods
of fabricating an organic field effect transistor that incorporates
a semiconductor material of the present teachings. The
semiconductor materials of the present teachings can be used to
fabricate various types of organic field effect transistors
including top-gate top-contact capacitor structures, top-gate
bottom-contact capacitor structures, bottom-gate top-contact
capacitor structures, and bottom-gate bottom-contact capacitor
structures.
FIG. 1 illustrates the four common types of OFET structures: (top
left) bottom-gate top-contact structure, (top right) bottom-gate
bottom-contact structure, (bottom left) top-gate bottom-contact
structure, and (bottom right) top-gate top-contact structure. As
shown in FIG. 1, an OFET can include a gate dielectric component
(e.g., shown as 8, 8', 8'', and 8'''), a semiconductor component or
semiconductor layer (e.g., shown as 6, 6', 6'', and 6'''), a gate
electrode or contact (e.g., shown as 10, 10', 10'', and 10'''), a
substrate (e.g., shown as 12, 12', 12'', and 12'''), and source and
drain electrodes or contacts (e.g., shown as 2, 2', 2'', 2''', 4,
4', 4'', and 4'''). As shown, in each of the configurations, the
semiconductor component is in contact with the source and drain
electrodes, and the gate dielectric component is in contact with
the semiconductor component on one side and the gate electrode on
an opposite side.
In certain embodiments, OTFT devices can be fabricated with the
present enantiomerically enriched mixture on doped silicon
substrates, using SiO.sub.2 as the dielectric, in top-contact
geometries. In particular embodiments, the active semiconductor
layer which incorporates the present enantiomerically enriched
mixture can be deposited at room temperature or at an elevated
temperature. In other embodiments, the active semiconductor layer
which incorporates the present enantiomerically enriched mixture
can be applied by spin-coating or printing as described herein. For
top-contact devices, metallic contacts can be patterned on top of
the films using shadow masks.
In certain embodiments, OTFT devices can be fabricated with the
present enantiomerically enriched mixture on plastic foils, using
polymers as the dielectric, in top-gate bottom-contact geometries.
In particular embodiments, the active semiconducting layer which
incorporates the present enantiomerically enriched mixture can be
deposited at room temperature or at an elevated temperature. In
other embodiments, the active semiconducting layer which
incorporates the present enantiomerically enriched mixture can be
applied by spin-coating or printing as described herein. Gate and
source/drain contacts can be made of Au, other metals, or
conducting polymers and deposited by vapor-deposition and/or
printing.
In various embodiments, a semiconducting component incorporating
the present enantiomerically enriched mixture can exhibit n-type
semiconducting activity, for example, an electron mobility of
10.sup.4 cm.sup.2/V-sec or greater and/or a current on/off ratio
(I.sub.on/I.sub.off) of 10.sup.3 or greater.
Other articles of manufacture in which the present enantiomerically
enriched mixture are useful are photovoltaics or solar cells. The
present enantiomerically enriched mixture can exhibit broad optical
absorption and/or a tuned redox properties and bulk carrier
mobilities. Accordingly, the present enantiomerically enriched
mixture described herein can be used, for example, as an n-type
semiconductor in a photovoltaic design, which includes an adjacent
p-type semiconductor to form a p-n junction. The present
enantiomerically enriched mixture can be in the form of a thin film
semiconductor, or a composite including the thin film semiconductor
deposited on a substrate.
The following examples are provided to illustrate further and to
facilitate the understanding of the present teachings and are not
in any way intended to limit the invention.
Unless otherwise noted, all reagents were purchased from commercial
sources and used without further purification. Some reagents were
synthesized according to known procedures. Anhydrous
tetrahydrofuran (THF) was distilled from sodium/benzophenone.
Reactions were carried out under nitrogen unless otherwise noted.
UV-Vis spectra were recorded on a Cary Model 1 UV-vis
spectrophotometer. NMR spectra were recorded on a Varian Unity Plus
500 spectrometer (.sup.1H, 500 MHz; .sup.13C, 125 MHz).
Electrospray mass spectrometry was performed on a Thermo Finnegan
model LCQ Advantage mass spectrometer.
EXAMPLE 1
Preparation of N,N'-bis((R)-substituted)-1,7 (or
1,6)-dicyanoperylene-3,4:9,10-bis(dicarboximide)
((R)--PDI-CN.sub.2)
A mixture of PDA-Br.sub.2 (1.83 g, 3.33 mmol) and an (R)-(-)-amine
(formula IIIa, IIIb, or IIIc) (1.05 g, 10.4 mmol) in 1,4-dioxane
(30 mL) was stirred in a sealed flask at 165.degree. C. for two
hours. Upon cooling to room temperature, the reaction mixture was
concentrated under vacuum. The residue was subjected to column
chromatography on silica gel using chloroform as the eluent to give
N,N'-bis((R)-substituted)-1,7 (or
1,6)-dibromoperylene-3,4:9,10-bis(dicarboximide)
((R)--PDI--Br.sub.2) (1.55 g, 65.1%).
A mixture of (R)--PDI--Br.sub.2 (0.35 g, 0.49 mmol) and CuCN (0.26
g, 2.9 mmol) in DMF (7 mL) was stirred at 150.degree. C. for 1
hour. Upon cooling to room temperature, the reaction mixture was
filtered to collect the insoluble materials, which were washed with
methanol thoroughly. This material was purified by column
chromatography on silical gel using chloroform (up to
chloroform:ethyl acetate=100:1, 100:4 slowly, v/v) as the eluent to
give (R)--PDI-CN.sub.2 (0.18 g, 61%).
EXAMPLE 2
Preparation of N,N'-bis((S)-substituted)-1,7 (or
1,6)-dicyanoperylene-3,4:9,10-bis(dicarboximide)
((S)--PDI-CN.sub.2)
A mixture of PDA-Br.sub.2 (12.0 g, 21.8 mmol) and an (S)-(+)-amine
(formula IIIa, IIIb, or IIIc) (6.2 mL, 45.8 mmol) in 1,4-dioxane
(180 mL) was stirred in a sealed flask at 165.degree. C. for one
hour. After cooling to room temperature, the solvent was removed
under vacuum. The solid residue was purified by column
chromatography with chloroform as the eluent to give
N,N'-bis((S)substituted)-1,7 (or
1,6)-dibromoperylene-3,4:9,10-bis(dicarboximide)
((S)--PDI--Br.sub.2) (9.52 g, 61.0%).
A mixture of (S)--PDI--Br.sub.2 (9.86 g, 13.76 mmol) and CuCN (7.26
g, 81.06 mmol) in DMF (160 mL) was stirred at 150.degree. C. for 1
hour. After cooling to room temperature, the reaction mixture was
filtered to collect the insoluble materials, which were washed with
methanol thoroughly. This crude product was subjected to column
chromatography on silical gel with chloroform (slowly up to
chloroform:ethyl acetate=100:4, v/v) as the eluent to give
(S)--PDI-CN.sub.2 (6.34 g, 75.7%).
EXAMPLE 3
Preparation of racemic N,N'-bis-substituted-1,7 (or
1,6)-dicyanoperylene-3,4:9,10-bis(dicarboximide) (PDI-CN.sub.2)
Hydroxylamine hydrochloride (23.2 g, 0.33 mol) was added to a
mixture of ketone 1 (16.3 g, 0.16 mol) and methanol (250 mL),
followed by addition of sodium acetate (34.2 g, 0.42 mol). This
suspension was vigorously stirred and refluxed for 2 hours. After
cooling to room temperature, most of the solvents were removed in
vacuo and the residue was poured into water (400 mL). This mixture
was extracted with Et.sub.2O (300 mL.times.2). The combined organic
layers were washed with water, saturated NaHCO.sub.3 and brine,
dried over Na.sub.2SO.sub.4, and concentrated on rotary evaporator,
leading to ketoxime 2 (17.6 g, 94%), which was used directly for
next step without further purification.
A solution of crude ketoxime 2 (17.6 g, 0.15 mol) in dry Et.sub.2O
(70 mL) was added dropwise to a suspension of LiAlH.sub.4 (11.0 g,
0.28 mol) in dry Et.sub.2O (110 mL) at 0.degree. C. After addition,
the mixture was refluxed for 16 hours, before it was cooled to
0.degree. C. by an ice/water bath. Water (15 mL) was added slowly
to the reaction mixture, followed by addition of an aqueous
solution of NaOH (15%, 15 mL) and water (15 mL) in sequence. The
reaction mixture was filtered, and the filtrate was dried over
Na.sub.2SO.sub.4, and concentrated on rotary evaporator. The
residue was distilled to afford the amine 3 as racemates (8.3 g,
54.2%).
A mixture of PDA-Br.sub.2 (1.80 g, 3.27 mmol) and amine 3 (racemic)
(1.0 g, 9.9 mmol) in 1,4-dioxane (30 mL) was stirred in a sealed
flask at 165.degree. C. for 1.5 hours. Upon cooling to room
temperature, the reaction mixture was concentrated under vacuum.
The residue was subjected to column chromatography on silica gel
using chloroform as eluent to give a racemic mixture of
N,N'-bis-substituted-1,7 (or
1,6)-dibromoperylene-3,4:9,10-bis(dicarboximide) (PDI--Br.sub.2)
(1.70 g, 72.6%).
A mixture of racemic PDI--Br.sub.2 (0.99 g, 1.39 mmol) and CuCN
(0.75 g, 8.37 mmol) in DMF (20 mL) was stirred at 150.degree. C.
for 1 hour. Upon cooling to room temperature, the reaction mixture
was filtered to collect the insoluble materials, which were washed
with methanol thoroughly. This material was purified by column
chromatography on silical gel using chloroform (up to
chloroform:ethyl acetate=100:1, 100:4, slowly, v/v) as the eluent
to give a racemic mixture of N,N'-bis-substituted-1,7 (or
1,6)-dicyanoperylene-3,4:9,10-bis(dicarboximide) (PDI-CN.sub.2)
(0.74 g, 87.5%).
EXAMPLE 4
Device Fabrication and Measurements
Thin-film transistor (TFT) devices (50-100 .mu.m channel lengths
(L) and 1.0-4.0 mm channel widths (W)) were fabricated using the
top-gate bottom-contact configuration with various mixtures of
stereoisomers of compounds of formula I incorporated as
semiconductor films. Semiconductors films were spin-coated from a
solution of chlorinated solvents (2-10 mg/mL) on top of Au
electrodes/glass substrates. Next, the gate dielectric layer was
spin-coated. Examples of gate dielectrics are PMMA, PS, PVA, PTBS
and have thicknesses of 300-1500 nm. The device was completed by
deposition of the gate contact. All electrical measurements were
performed in ambient atmosphere. Data reported below are average
values measured from at least three devices tested at different
locations on the semiconductor film.
To allow comparison with other organic FETs, mobilities (.mu.) were
calculated by standard field effect transistor equations. In
traditional metal-insulator-semiconductor FETs (MISFETs), there is
typically a linear and saturated regime in the I.sub.DS vs V.sub.DS
curves at different V.sub.G (where I.sub.DS is the source-drain
saturation current, V.sub.DS is the potential between the source
and drain, and V.sub.G is the gate voltage). At large V.sub.DS, the
current saturates and is given by:
(I.sub.DS).sub.sat=(WC.sub.i/2L).mu.(V.sub.G-V.sub.t).sup.2 (1)
where L and W are the device channel length and width,
respectively, C.sub.i is the capacitance of the gate dielectric,
and V.sub.t is the threshold voltage.
Mobilities (.mu.) were calculated in the saturation regime by
rearranging equation (1):
.mu..sub.sat=(2I.sub.DSL)/[WC.sub.i(V.sub.G-V.sub.t).sup.2] (2)
The threshold voltage (V.sub.t) can be estimated as the x intercept
of the linear section of the plot of V.sub.G versus
(I.sub.DS).sup.1/2.
Table 1 describes different stereoisomeric mixtures of a compound
of formula I obtained by mixing (S,S)-enantiomers and
(R,R)-enantiomers of I in the molar ratio shown below:
TABLE-US-00001 TABLE 1 Semiconductor Mixture of I (S,S)-Enantiomer
(%) (R,R)-Enantiomer (%) CZH-V-107: 0 100 CZH-V-154A: 90 10
CZH-V-154B 80 20 CZH-V-154C 70 30 CZH-V-154D: 60 40 CZH-V-154E: 50
50
FIG. 2 compares the mobilities of TFTs incorporating the different
semiconductor mixtures in Table 1.
Table 2 describes different stereoisomeric mixtures of a compound
of formula I prepared by cyanating an anhydride of formula II with
a mixture of S-amines and R-amines in the molar ratio given
below:
TABLE-US-00002 TABLE 2 Semiconductor Mixture of I S-Amine (%)
R-Amine (%) JB1.18 100 0 CZH-V-107: 0 100 CZH-V-141A 90 10
CZH-V-141B 70 30 CZH-V-93M 50 50
FIG. 3 compares the mobilities of TFTs incorporating the different
semiconductor mixtures in Table 2.
Referring to FIGS. 2 and 3, it can be seen that an enantiomerically
enriched mixture according to the present teachings, where
(R,R)-stereoisomers:(S,S)-stereoisomers (or vice versa) is between
about 0.8:0.2 and about 0.98:0.02 (e.g., CZH-V-154A, CZH-V-154B, or
CZH-V-141A), exhibited a mobility that is at least two times higher
than the racemate (e.g., CZH-V-154E or CZH-V-93M). In addition, the
mobilities measured from these enantiomerically enriched mixtures
were not statistically different compared to devices made with
optically pure enantiomers (e.g., CZH-V-107 or JB1.18).
The present teachings encompass embodiments in other specific forms
without departing from the spirit or essential characteristics
thereof. The foregoing embodiments are therefore to be considered
in all respects illustrative rather than limiting on the present
teachings described herein. The scope of the present teachings is
thus indicated by the appended claims rather than by the foregoing
description, and all changes that come within the meaning and range
of equivalency of the claims are intended to be embraced
therein.
* * * * *